[The flavor-text and abilities are pretty close to the Hackmaster model here, but the name’s been changed. This monster was originally called a nidhogg, which is, of course, a real (and individual) Norse legendary dragon. But although the visuals are arguably the same, the flavor text is completely different. Since it guards magical treasures, couldn’t they have at least called it a fafnir?]
Watchwyrm This
immense dragon has a serpentine body with four rudimentary legs. A crest of
long spines decorates its back.
A watchwyrm is a draconic
creature that devotes its entire life to the defense of one particular magical
site or item. Enchanted pools, stable portals, nexuses of ley lines or even
particularly interesting haunts attract their attention and service, and a
watchwyrm will fight to the death in order to keep its chosen ward safe and
secure. That does not necessarily mean unused, however, but the watchwyrm
ensures that only worthy candidates are allowed the powers of its site. Different
watchwyrms have different definitions of “worthy”, ranging from those that pay
a tithe to creatures that can defeat them in a riddle contest to demanding an
animal or sapient sacrifice.
Watchwyrms vary somewhat in
alignment, but they are all lawful. Their origins are somewhat mysterious, as
they live solitary lives and do not seem to breed. Some scholars hypothesize
that a suitable treasure spontaneously generates a watchwyrm, whereas others
suppose that they are born as another species of dragon and then transform
through service. Whatever the case is, watchwyrms do not look kindly on those
that ask too many probing questions about their backgrounds.
In combat, watchwyrms do
whatever they can to prevent their guarded relic from being stolen or polluted.
They can cast spells as sorcerers do, but most watchwyrms favor defensive or
divinatory spells over those that are direct offense. Their powerful jaws,
crushing coils and fiery breath usually see to wounding or killing foes.
Watchwyrms are imbued with a supernatural connection to their warded site or
item, and if fighting in defense of it, a watchwyrm can be imbued with
supernatural alacrity when hard pressed.
A watchwyrm grows about
thirty feet long and is as thick as a man’s torso. If not slain violently, they
can live a thousand years or more.
Shores of Swords 